Hydraulic precontrol of pressure fluid operated governors



Nov. 4, 1952 o. s. RUUD ErAL HYDRAULIC PRECON'IIROL OF PRESSURE FLUID OPERATED GOVERNORS Filed Dec. 29, 194'7l Patented Nov. 4, 1952 @FFlCE HYDRAULIC PRECONTROL F PRESSURE FLUID OPERATED GGVERNORS Otto Severin Ruud and Trygve Johan Wilhelmsen, Oslo, Norway Application December 29, 1947, Serial N0. 794,220 In Norway March 8, 1946 Section 1, Public Law 690, August 8, 1946 Patent expires March 8, 1966 Claims.

The present invention relates to a hydraulic pre-control for pressure fluid operated governors for prime movers, turbines, motors and the like of the type in which the movements of a centrifugal pendulum by throttling of a uid outlet acts upon a piston (the pendulum piston) which is in hydraulic communication with the source of pressure fluid at one side and with the distribution slide of the servomotor at the other side, the movements of said pendulum acting upon a distrbution slide that governs a servomotor in accordance with the movements of the centrifugal pendulum.

In pre-controls or relays ,of this type diliculties have been met as regards obtention of a desired return or compensation curve, because dierent pressures were acting at opposite sides of the pendulum piston and because the communication between said opposite sides took place through openings or slots the cross sectional areas of which were increasing or decreasing during the movements of the piston. The dimensions of such openings or slots had to be corrected during the operation of the apparatus since they could not be quite accurately determined beforehand.

The present invention aims at providing a precontrol of the type specied the action of which, and especially the compensating operation of which may be exactly predetermined.

According to the invention the pressures at opposite sides of the pendulum piston are of equal value in middle position of said piston. Preferably such pressure is maintained at a value between 1/3 and of the value of the pressure of the pressure fluid source.

In this connection there is, in a hydraulic communication between the front and rear sides of the pendulum piston, inserted a throttle member the bore ofwhich is chosen in accordance with the period of compensation desired. This arrangement allows for an exact predetermination of the period of compensation only by making use of a throttle bore having a corresponding cross sectional area.

The invention Will be more fully described with reference to the accompanying drawing that by way of example shows a somewhat diagrammatical illustration of an embodiment thereof.

The pre-control, which simultaneously forms a resilient link in the return movement, comprises a'cylinder or piston housing I in which is displaceably mounted a sleeve 2, that near its iront end is provided with a shoulder 2 .that acts as a piston surface and closes off an annular space 3.

Within the sleeve 2 is slidably a piston 4 having guide projections 5 and 6, slidable respectively in an opening in the closed front end of sleeve 2 and in an end member I screwed into the rear end of the sleeve. On opposite sides of the piston 4 are provided springs 8, these springs may have like characteristics and maintain the piston 4 in a predetermined normal position within the sleeve 2, a space 9 being formed in front of and a space I0 in rear of the piston.

The front guide projection 6 of the piston has a longitudinal bore II that through a channel I2 communicates with the space I0 behind the piston. In front of channel l2 is inserted a throttle I3 having a narrow opening which establishes communication between spaces 9 and I0, the bore I I communicating with space 9 through an opening I4.

Into the end of bore II is screwed a nozzle I5, the exit opening of which is controlled by a throttle-disc I6 receiving its movement from a pendulum governor I1 of usual construction driven by the machine to be governed.

Through a channel I8 the annular space 3 communicates with space 9 in front of the piston 4.

Pressing against the end member 'I of sleeve 2 is a screw I9 threaded into a nut that is rotatably journalled in one lever 2Q of a bell-crank pivotable on a projection 2| extending rearwardly from the housing I. i

The controlling shaft of the machine to be controlled is designated by numeral 22 and carries fixed thereon a control arm 23 connected to the piston 24 of the servomotor, whereby said piston 24 may cause shaft 22 to swing in either direction, according to the control action operated. To said control arm is attached one end of a rod 25 the other end of which is connected .tothe other lever of the bell-crank above mentioned, that is pivoted on the housing I. The rod vmay be attached at different distances from the pivot of said bell-crank whereby the effective length of the lever 20' may b-e adjusted.

The control arm 23 also carries an'arm26 to which is secured-at a desirable, shiftable pointthe lower end of a piston rod 26', the top end of which carries a piston 21 reciprocating inabore 28 in a housing 29 of the distribution slide.; The latter has two diameters of which the smallest one 30 is provided with two guide edges serving to control the supply of fluid to and from the piston space 3| at the large end of the servomotor. ,To the distribution slide pressure fluid is admitted through a supply conduit 33 extending to thevpiston space 35 at the small end of the servomotor.

The large area 30 of the distribution slide serves to balance the slide between full pressure at the under side thereof and about half pressure at the top side. The space above 30 communicates through a channel 36 withY the space 28 above piston 21 which latter serves as return piston. The space above the distribution slide 30 also communicates with lthe space IIB behind the pendulum piston 4, by means of a tube 31. The annular space 3 in the house communicates with the conduit 33 through a tube 38.

The arrangement described operates as follows:

In the position shown in the drawing, which may be called a normal position, the annular space 3 is subjected to full pressure, which corresponds to the pressure of the oil coming from the source of pressure, and which pressureY is pressing the sleeve 2 towards left, the latter abutting against the screw I9. From the annular space 3 oil fiows through channel I8 and lls chamber 9, from which oil flows through the opening |4, the throttle I3 and the channel I2 to the space Il) and at the same time a jet of oil issues through the nozzle I5 against the throttling plate I6.

Thus both sides of piston 4 are in hydraulic communication with each other through the throttle I3, and the cross section of the bore in the latter determines the period of the resilient returnmovement of the'piston, that is, the compensation period. Y

The diameter of the channel I8 extending from the annular space 3 and the flow through the nozzle I5 are so adjusted that in middle position of the slide the pressure in spaces 9 and I0 amounts to about half of the pressure within the annular space 3. This pressure acts from space ||l through conduit 31 on the top side of the distribution slide 30' and is balancing the distribution slide in middle position thereof.

If the load on the controlled machine decreases the pendulum. I1 causes the throttle plate l5, to move towards the nozzle I5 and to close the outlet thereof. Thereby the pressure within space 9 increases, and the piston 4 is moved rearwardlyl within the sleeve 2. Oil is then driven from space II) through conduit 31 to the space above the distribution slide 39 and the latter 1s moved downwards from middle position, whereby oil under pressure is supplied to the serv-omotor chamber 3|, and piston 24 and thus also arm 23 are moved towards left, which is the closed position. During the swinging movement of arm 23 the piston 21 is moved downwards and draws the excess of oil above slide 30 into the space 2B, so that the distribution slide returns to middle position and the movement of the servomotor piston stops. y When the governor shaft 22 has had imparted thereto the closing movement necessary, the distribution slide is moving back to its middle position, the number of revolutions of the pendulum I1 is decreased, whereby the throttle plate I6 is moved away from the nozzle I5, so that a jet may again issue from the latter. Thereby the pressure within space 9 sinks and the spring 8 in space I0 presses the piston 4 forwards, that is, to the right, and simultaneously oil successively flows through throttle I3 into space I0.

When the number of revolutions of the pendulum I1 has again become normal, equilibrium has been reestablished between the forces acting upon the piston 4 and the latter stops.

If the load on the machine increases the nums ber of revolutions of pendulum I1 decreases and moves the throttle plate I6 away from the nozzle I5. The pressure within the space 9 then sinks and piston 4 moves towards right. Hereby a decrease of pressure takes place within space I0 and is transmitted to the space above the distribution slide, whereby the latter is raised and allows oil to ow out of chamber 3| of the servomotor, so that piston 24 is moved towards right and rotates the shaft 22 accordingly, whereby move driving force is supplied to the machine. Simultaneously piston 21 is moved upwards and presses oil through channel 36 to the space above the distribution slide 30', which latter is thereby driven to its middle position.

When the governor has caused that suicient force is supplied to the machine the number of revolutions of pendulum I1 increases and moves the throttle plate I6 towards the nozzle I5 whereby the pressure within space 9 again rises to normal value. During this period the spring 8 within space 9 slowly moves piston 4 left into normal position thereof, oil being driven from space I0 through the throttle I3 and entering space 9 until equilibrium is again obtained and the movef ment stops.

When sleeve 2 is displaced towards the throttle plate I6 the revolutions decrease, and when it is displaced in the opposite direction the revolutions increase. Since sleeve 2 has a smaller diameter outside the space 3 than at the inside thereof, the constant oil pressure in space 3 urges sleeve 2 away from the pendulum. This pressure is taken up by the screw I9 in the lever 20.

Increasing revolutions cause the piston 4 to move towards the left, and oil is pressed through pipe 31 to the upper side of the slide 30 by which the same is moved downwards away from its normal position and allows oil from the conduit 33 to flow through conduit 32 to a cylinder 3| so as to move the piston 24 towards the left in closing direction. This movement is transmitted through the control arm 23 and shaft 22 to the apparatus controlling the supply of water to the turbine in order to decrease such supply. At the same time the rod 25 is pushed upwards and moves the'screw I9 to the left allowing the oil pressure within the space 3 to move the sleeve 2 to the left and away from the pendulum whereby the revolutions are automatically increased. The position of piston 4 in relation to the sleeve 2 is not changed during this movement. The extent of the movement of sleeve 2 may be varied by adjusting the e'Tective length of lever 20', whereby the governoris given the necessary degree of lag for parallel operation of a number of machines.

The object of this movement is to obtain a greater number of revolutions of a controlled machine at decreasing load and a smaller number of revolutions at increasing load. The difference in the number of revolutions of the machineY when idling and when at maximumload is necessary for obtaining a correct distribution of thev load between a number of simultaneously runningfalternating current machines. A y Y,

vThe length of the stroke of piston 21, that serves to return the distribution slide, may be Varied by adjusting the point where the piston rod 26 is attached tothe arm 2B, thus the intensity of the return operation may be varied according to desire. f

The bore of the throttle I3Vin the pendulum piston 4determines the period of thev resilient return movement (the compensation period) and accordingly the length of said period is determined by giving said bore a desired cross sectional area. As the said bore is acting to compensate for both directions of movement of piston 4 springs 8 having different characteristics may be used if a different length of compensation period for opening and for closing is desired. It is possible to arrange the communication between front and rear side of the pendulum piston, with the throttle I3 therein, exterior of the piston.

We claim:

1. A stabilizing mechanism of the type wherein a centrifugal governor cooperates with a servomotor to regulate the speed of a machine comprising, in combination, a fluid pressure system for operating the servomotor; a first cylinder; a slide member moving in said iirst cylinder; valve means operated by said slide member and adapted to actuate the servomotor; a housing; a second cylinder disposed in said housing; a piston operating in said second cylinder having two action faces, said piston dividing said second cylinder into a first and a second chamber; two spring means in said second cylinder, one in each of said chambers, oppositely acting one on each face of said piston and tending to keep said piston in a middle position corresponding to a normal speed of the machine; a passage providing a permanent communication between said iirst and said second chamber; a pressure chamber adjacent to said first chamber of said second cylinder; a narrow passage providing a fluid communication between said pressure chamber and said lirst chamber of said second cylinder; duct means providing a fluid communication between said pressure system and said pressure chamber; a duct providing a fluid communication between said second chamber of said second cylinder and said first cylinder; a fluid outlet provided in said first chamber of said second cylinder; a centrifugal governor; a nozzle valve operated by said centrifugal governor to open and close said iiuid outlet, thereby causing a movement of said piston changing the pressure in said second chamber of said second cylinder whereby said slide member in said first cylinder is set in motion so that said valve means actuate the servomotor; and adjustable means for returning said slide means and said valve means to a normal position after regulation of the machine has been effected.

2. A stabilizing mechanism of the type wherein a centrifugal governor cooperates with a servomotor to regulate the speed of a machine comprising, in combination, a fluid pressure system for operating the servomotor; a first cylinder; a slide member moving in said first cylinder; valve means operated by said slide member and adapted to actuate the servomotor; a housing; a second cylinder disposed in said housing; a piston operating in said second cylinder having two action faces, said piston dividing said second cylinder into a first and a second chamber; two spring means in said second cylinder, one in each of said chambers, oppositely acting one on each face of said piston and tending to keep said piston in a middle position corresponding to a normal speed of the machine; a passage providing a permanent communication between said iirst and said second chamber; a throttle member disposed in said passage and adapted to effect a predetermined length of the period of action of said piston; a pressure chamber adjacent to said rst chamber of said second cylinder; a narrow passage providing a fluid communication between said pressure chamber and said iirst chamber of said second cylinder; duct means providing a fluid communication between said pressure system and said pressure chamber; a duct providing a fluid communication between said second chamber of said second cylinder and said first cylinder; a iiuid outlet provided in said first chamber of said second cylinder; a centrifugal governor; a nozzle valve operated by said centrifugal governor to open and close said fluid outlet, thereby causing a movement of said piston changing the pressure in said second chamber of said second cylinder whereby said slide member in said first cylinder is set in motion so that said valve means actuate the servomotor; and adjustable means for returning said slide means and said valve means to a normal position after` regulation of the machine has been effected.

3. A stabilizing mechanism of the type wherein a centrifugal governor cooperates with a servomotor to regulate the speed of a machine comprising, in combination, a iiuid pressure system for operating the servomotor; a first cylinder; a

slide member moving in said iirst cylinder; valvev means operated by said slide member and adapted to actuate the servomotor; a housing; a second cylinder disposed in said housing; a piston operating in said second cylinder having two action faces, said piston dividing said second cylinder into a first and a second chamber; two spring means in said second cylinder, one in each of said chambers, oppositely acting one on each face of said piston and tending to keep said piston in a middle position corresponding to a normal speed of the machine, said spring means having different characteristics so as to render the time period for compensation diiierent according to the direction of the movement of said piston; a passage providing a permanent communication between said rst and said second chamber; a pressure chamber adjacent to said rst chamber of said second cylinder; a narrow passage providing a fluid communication between said pressure chamber and said iirst chamber of said second cylinder; duct means providing a fluid communication lbetween said pressure system and said pressure chamber; a duct providing a fluid communication between said second chamber of said second cylinder and said first cylinder; a fluid outlet provided in said iirst chamber of said second cylinder; a centrifugal governor; a nozzle valve operated by said centrifugal governor to open and close said fluid outlet, thereby causing a movement of said piston changing the pressure in said second chamber of said second cylinder whereby said slide member in said first cylinder is set in motion so that said valve means actuate the servomotor; and adjustable means for returning said slide means and said valve means to a normal position after regulation of the machine has been effected.

4. A stabilizing mechanism of the type wherein a centrifugal governor cooperates with a servomotor to regulate the speed of a machine comprising. in combination, a fluid pressure system for operating the servomotor; a iirst cylinder; a slide member moving in said rst cylinder; valve means operated by said slide member and adapted to actuate the servomotor; a housing; a second cylinder disposed in said housing; a piston operating in said second cylinder having two action faces, said piston dividing said second cylinder into a iirst and a second chamber; two spring means in said second cylinder, one in each of said chambers, oppositely acting one on each face of said piston and tending tokeep said piston'in a middle position correspondingr to a normal speed of the machine; a passage providing a permanent communication between said rst and said second chamber; a pressure chamber adjacent to said rstchamber of said second cylinder; a narrow passage providing a uid communication between said pressure chamber and said iirst chamber of said second cylinder; duct means providing a iiuid communication between said pressure system and said pressure chamber; a duct providing a fluid communication between said second chamber of said second cylinder and said iirst cylinder; a uid outlet providedV in said rst chamber of said second cylinder; a centrifugal governor; a nozzle valve operated by said centrifugal governor to o'pen and close said iiuid outlet, thereby causing a movement of said piston changing the pressure in said second chamber of said second cylinder whereby said slide member in said rst cylinder is set in motion so that said valve means actuate the servomotor; adjustable means for returning said slide means and said valve means to a normal position after regulation of the machine has been effected; and adjustable means for automatically displacing said second cylinder in said housing causing a relative movement between said second cylinder and said piston whereby the controlling action of said piston is delayed.

5. A stabilizing mechanism of the type wherein a centrifugal governor cooperates with a servomotor' to regulate the speed of a machine comprising, in combination, a fluid pressure system for operating the servomotor; a first cylinder; a slide member moving in said first cylinder; valve means operated by said slide member and adapted to actuate the servomotor; a housing; a second cylinder disposed in said housing; a piston operating in said second cylinder having two action faces, said piston dividing said second cylinder into a rst and a second chamber; two spring means in said second cylinder, one in each of Said chambers, oppositely acting one on each face of said piston and tending to keep said piston in a middle position corresponding to a normal speed of the machine, said spring means having different characteristics so as to render the time period for compensation different according to the direction of the movement of said piston; a passage providing a permanent communication between said rst and said second chamber; a throttle member disposed in said passage and adapted to effect a predetermined length of the period of action of said piston; a pressure chamber adjacent to said rst chamber of said second cylinder; a narrow passage providing a fluid communication between said pressure chamber and said rst chamber of said second cylinder; duct means providing a fluid communication between said pressure system and said pressure chamber; a duct providing a iiuid communication between said second chamber ofY said second cylinder and said first cylinder; a iiuid outlet provided in said first chamber of said second cyl-y inder; a centrifugal governor; a nozzle Valve op-Y erated by said centrifugal governor to open and close said fluid outlet, thereby causing a movement of said piston changing the pressure in said second chamber of said second cylinder whereby said slide member in said iirst cylinder is set in motion so that said valve means actuate thev servomotor; adjustable means for returning said slide means and said valve means to normal position after regulation of the machine has been effected; and adjustable means for autonf'iaticallyl displacing said second cylinder in said housing causing a relative movement between said second cylinder and said piston whereby the controlling action of said piston is delayed.

OTTO SEVERIN RUUD.

TRYGVE JOHAN WILHELMSEN.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 2,110,622 Fischel Mar. 8, 1938 2,153,381 Maas Apr. 4, 1939 2,353,692 Cunningham July 18, 1944 2,379,304 Kalin June 26, 1945 FOREIGN PATENTS Number Country Date 87,631 Switzerland Dec. 16, 1920 96,933 Switzerland Nov. 16, 1922 99,383 Switzerland June 16, 1923 151,030 Switzerland Feb. 1, 1932 50,782 Norway May 2, 1932 

